As a child, you were probably told to ‘eat your carrots’ so you could see at night. Or forced to swallow a spoonful of cod liver oil every day. Like with many old sayings and practices, there’s often a nugget of wisdom contained within them. With carrots and cod liver oil, it was the health benefits of the fat soluble vitamins A and D. One of the downsides of the low-fat diet frenzy in the last few decades has been reduced intake of these important vitamins that have key roles in your body.
The story you were told about carrots was true: they contain lots of beta-carotene, the plant form of vitamin A that’s converted by your digestion to the retinyl (animal) form. Eggs, cod liver oil and liver (offal) are good sources of the animal form of vitamin A. Your body readily absorbs and stores vitamin A because it’s so important for strong eyesight, healthy skin, and resilient mucous membranes (including your bowel lining). Green vegetables are also a good source of beta-carotene.
A fact that’s not well known is that although vitamin A is easily absorbed and stored, zinc is needed to extract it from storage; so people low in zinc can seem to be deficient in vitamin A, even though they really aren’t.
Another important fat soluble vitamin is the ‘sunlight vitamin’, vitamin D. It’s absorbed through your skin and also through vitamin D-rich food like oily fish (including cod liver oil) and eggs. Converting sunlight to active vitamin D is a multi-step process that requires input from your liver and kidneys. Once converted, vitamin D plays an important role in regulating your body’s calcium balance and bone health.
Keep in mind that there are two other factors to consider (besides what was eaten) when working out how a vitamin deficiency could have happened. The first one, most important but easily overlooked, is to investigate how well you’re absorbing those vitamins. An unhealthy bowel lining won’t work as efficiently as it should, so vital nutrients might slip past. The other consideration is prescription medications; some of them can impact on the uptake of certain nutrients, including fat soluble vitamins.
You probably noticed while reading that certain foods are especially valuable sources of the fat soluble vitamins A and D: Eggs, carrots, green vegetables, oily fish, liver. You could check your meal plan for them. And maybe consider resuming your childhood practice of a daily spoonful of cod liver oil. Maybe.